Mainspring arbor for timepieces



E. H. HORN.

MAINSPRING ARBOR FOR TIMEPIECES.

APPLICA'HON FILED MAY6,192L

Patsnted Nov. 14, 1922.

Patented Nov. 14, 1922.

UNITED STATES PATENT OFFICE.

ERNEST H. HORN, OF WATERBURY, CONNECTICUT, ASSIGNOR TO WATERBURY CLOCKCO., OF WATERIBURY, CONNECTICUT,

A CORPORATION.

MAINSPRING ARBOR FOR TIMEPIECES.

Application filed May 6,

To all whom it may concern:

Be it known that I, ERNEST H. HORN, a citizen of the United States,residing at WVaterbury, in the county of New Haven and State ofConnecticut, have invented a new and useful Improvement in MainspringArbors for Timepieces; and I do hereby declare the following, when takenin connection with the accompanying drawings, and the characters ofreference marked thereon, to be a full, clear, and exact description ofthe same, and which said drawings constitute part of this application,a'nd'represent in Fig. 1 a perspective View of a main-spring arborconstructed in accordance with my invention.

Fig. 2 a plan view thereof with the inner end of the main-spring shownas applied to the annular notched rib of the arbor-hub.

Fig. 3 a detached plan view of the inner end of the main-spring showingits conpling-slot.

Fig. 4 a view of the arbor in end elevation with the inner end of themain-spring in longitudinal section and shown in the position which thesaid end assumes when the spring is unwound, at which time the end ofthe spring engages with the safety-abutment of the arbor.

Fig. 5 a corresponding view showing the spring as wound and its innerend as engaged with the draft-abutment of the arbor.

Fig. 6 a sectional view on the line 66 of re.

1y invention relates to an improved main-spring arbor for time-pieces,the object being to produce, at a low cost for manufacture, a simple andreliable arbor constructed to provide not only an improved integraldraft-abutment but also a safetyabutment arranged to prevent the springfrom disengaging itself from the arbor when the spring is unwound.

With these ends in view, my invention consists in a main-spring arborfor timepieces characterized by an annular rib transversely notched toproduce, at one operation, a draft-abutment engaged by the inner end ofthe spring when the same is wound and an opposed safety-abutmentpositioned to be engaged by the extreme inner end of the spring when thesame is unwound.

My invention further consists in a main- 1921. Serial No. 467,390.

spring arbor ior timepieces having certain details of construction aswill be hereinafter described and pointed out in the claim.

In carrying out my invention, as herein shown, I employ a main-springarbor 6, having trunnions 7 and 8, a faced-off couplingshoulder 9 and ahub 10 of approved construction. The hub 10, which slightly exceeds thewidth of the main-spring 11, is formed with a centrally-arranged.integral, annular rib 12, which, by a single milling "operation, istransversely cut through to form a segmental notch 13, the bottom ofwhich coincides in curvature with; the eriphery of the hub. The cuttingof the notch 13 results in the production of what, for convenience, Ishall call a draft-abutment 14 and a corresponding safety-abut ment 15,these abutments facing each other and being tangential to the peripheryof the hub and, therefore, hook-like in their relations to the ends ofthe coupling-slot 16 in the inner end of the spring 11, in which thesaid slot, (which is a trifle wider than the width of the rib 12, asshown. in Figure 2,) is placed with regard to the extreme end of thespring, so as to produce a transverse tie-piece 17, narrower than thelength of the said notch. WVhen the spring is applied to the arbor, thetie-piece 17 enters the notch 13, as shown in Figures 2, 4t and 5. Then,when the spring is placed under tension, the forward edge 18 of thetie-piece is engaged with the draft-abutment 14, as shown in Figure 5.Now, in the event of an excessive unwinding of the spring, the inner endthereof is driven back in the notch 13, at which time the outer edge 19of the tiepiece is crowded against the safety-abutment 1.5 and thespring prevented from disengaging itself from the arbor, which 'is, inarbo-rs as ordinarily constructed, a frequent source of annoyance,calling for a considerable expenditure of time on' the part of jewelersand watchmakers doing repairing and cleaning operations.

My improved arbor is easy produce, since the draftand safety-abutmentsof its annular rib are produced by a single milling operation, which ismuch cheaper than upsetting the metal to form an integral hook and alsomuch cheaper than to insert a separate pin to form a drafthook, to saynothing of the advantage seand cheap to cured, under my invention by theconcurrent production of a safety-abutment, as described.

I claim:

A main-spring arbor for time-pieces the said arbor having a hub formedwith a cen-r trally located, integral, annular rib provided with atransverse segmental notch, the end Walls of Which are opposed to eachother and respectively constitute draftand safety-abutments and thefloor of which conforms in curvature to the curvature of the said hub.

In. testimony whereof, I have signed this specification in the presenceof two suh- 15 scribing Witnesses.

ERNEST H. HQRN. Witnesses:

J. R. PUTNAM,

C. H. HALL.

